1. Field of Invention
The invention relates to an ink cartridge for supplying ink to a recording head. In particular, the invention relates to an ink cartridge capable of preventing ink leakage from an ink supply hole by providing a filter in the ink supply hole.
2. Description of Related Art
Various conventional ink cartridges for supplying ink to a recording head of an ink jet recording apparatus are known. For example, an ink cartridge including a porous member impregnated with ink and contained in a cartridge case is known, and an ink cartridge wherein the interior of a cartridge case is divided into an ink chamber containing ink and a foam chamber containing a porous member impregnated with ink is also generally known.
U.S. Pat. No. 5,509,140 discloses an ink cartridge having an ink chamber and foam chamber wherein an ink supply hole is formed in the foam chamber-side portion of the cartridge case. Japanese Unexamined Patent Publication Nos. Hei 6-238908 and Hei 6-255122 disclose an ink cartridge having an ink chamber and a foam chamber wherein an ink supply hole is formed in the ink chamber-side portion of the cartridge case.
In the ink chamber disclosed in U.S. Pat. No. 5,509,140, a portion of a porous member near an ink supply hole elastically deforms to provide clearance for a joint member when the joint member protruding from a side of a recording head is inserted into the ink supply hole. A filter provided at an end of the joint member is pressed against the porous member so that an amount of ink impregnating the porous member can be supplied to the recording head. In addition to the ink supply hole, an atmosphere communicating hole is provided in the foam chamber-side portion of the ink cartridge. When the amount of ink impregnating the porous member in the foam chamber for supplying ink to the recording head decreases, the porous member is replenished with an amount of ink from the ink chamber. A negative pressure caused in the ink chamber by the supply of ink into the foam chamber is offset by air introduced into the ink chamber through the atmosphere communicating hole.
Japanese Unexamined Patent Publication No. Hei 6-238908 discloses an ink cartridge in which an elastic seal member is provided at an end portion of the ink supply hole. A filter for filtering debris, dust particles or similar material from the ink is provided in an ink passage formed in a partition that separates an ink chamber and a foam chamber. When the ink cartridge is set into a holder, a hollow needle protruding from a recording head side of the holder penetrates an elastic seal member in the ink cartridge and enters a supply hole to supply ink from the ink chamber to the recording head. When the amount of ink in the ink chamber decreases, the ink chamber is replenished with an amount of ink from the impregnated porous member provided in the foam chamber. A negative pressure caused in the foam chamber by the supply of ink into the ink chamber is offset by air introduced into the foam chamber through an atmosphere communicating hole.
Japanese Unexamined Patent Publication No. Hei 6-255122 discloses an ink cartridge in which an ink supply hole is formed in a lower portion of the ink chamber in a cartridge case. A filter is provided at an ink chamber-side end of an ink supply hole. An ink jet recording head communicating with the ink supply hole is firmly connected to or formed together with a lower portion of the cartridge case. The ink cartridge can be used with an ink jet recording apparatus that ejects ink downwardly to record on a recording medium.
A number of problems and disadvantages are present in the related art devices. In particular, in U.S. Pat. No. 5,509,140, ink is held in the porous member and does not leak even if the ink supply hole is directed downward while the ink cartridge is being attached to the recording head. However, if a wall of the ink cartridge is strongly pressed while the ink cartridge is being attached to the recording head, the porous member compresses and may leak ink from the ink supply hole, thereby staining the exterior or interior of the recording apparatus.
In Japanese Unexamined Patent Publication No. Hei 6-238908, it is necessary to fix the filter to the partition inside the cartridge case during manufacture of the ink cartridge. The fixation of the filter requires a great amount of labor because welding of the metal filter and the synthetic resin partition is very difficult.
Due to the provision of the elastic seal member at the ink supply hole in addition to the filter, the number of component members is great and the structure is complicated. Accordingly, production cost is considerably increased.
Further, it is difficult to attach and detach the ink cartridge to and from the holder because the hollow needle protruding from the recording head side of the holder must be aligned with and penetrate through the elastic seal member.
In Japanese Unexamined Patent Publication No. Hei 6-255122, the ink cartridge and the recording head are firmly connected or formed together. Accordingly, there is no consideration of preventing ink leakage as would be expected if the ink cartridge were detachable from the recording head.
In addition, during manufacture of the ink cartridge, the filter must be fixed to an ink chamber-side portion of the ink supply hole by placing it thereto from the inside of the cartridge case. Because it is difficult to weld the metal filter and the synthetic resin cartridge case, mounting the filter is difficult.
The industry lacks an inexpensive, easily manufactured ink cartridge that is detachable and easily replaceable and does not leak during replacement.